1. Field of the Invention
The present invention relates generally to the field of electrical angle and angle rate measurements and more particularly to circuits for electrically deriving signals proportional to an angle error and an angle rate as represented by synchro or resolver signals.
2. Description of the Prior Art
Conventional systems for deriving angular rate and angular error signals from three-wire signal information have employed elecrtro-mechanical devices which convert the shaft speed or shaft position of a servomotor to electrical signals representative of the angular rate or error. Recently developed techniques for the derivation of angular error signals, to eliminate necessity for the utilization of electro-mechanical devices, involve complex analog phase shifting circuitry, complex digital techniques requiring analog-to-digital conversion circuitry such as that taught in U.S. Pat. No. 3,376,570 issued to A. D. Lawson and complex quadrant switching which requires special techniques for transient suppression such as that taught in U.S. Pat. No. 3,848,172, issued to R. E. Thomas; both of the aforementioned patents being assigned to the assignee of the instant application. Additionally, techniques have been developed for the derivation of angular rate signals that require non-similar redundant signals which are non-linearly processed as taught in U.S. Pat. No. 3,568,960, issued to C. D. Griffith and cross-multiplication of sine and cosine signals derived from a Scott T transformer as taught in U.S. Pat. No. 3,514,719, issued to N. H. Rhodes. These prior art techniques are generally complex and costly, and a cheaper, simpler technique is desirable.
The present invention is directed to a simple method for deriving both angular error and angular rate signals, which does not require quadrant switching with its concomittant transient suppression, analog-to-digital conversion, or the use of a Scott T transformer for the generation of sine and cosine signals.